High-Salinity Wastewater Evaporator Heat Exchange Coiltube — 2507 Super Duplex / Titanium Grade
Product Code: JX-CT-182 | Category: Environmental Water Treatment — Industrial Wastewater Evaporation Systems
1. Product Overview
This coil tube product is specifically engineered for Multi-Effect Evaporator (MEE) and Multiple-Effect Distillation (MED) systems processing high-salinity industrial wastewater. Designed by Wenzhou Jixing Metal Materials Co., Ltd, this coiltube solution addresses the extreme corrosion and fouling challenges encountered when treating wastewater with chloride ion (Cl⁻) concentrations exceeding 50,000 ppm. The product incorporates 2507 Super Duplex Stainless Steel (UNS S32750) and Titanium (Ti Grade 1/2) tube materials, combined with a forced-circulation hydraulic design and integrated online cleaning interfaces to ensure reliable long-term operation in the harshest evaporative environments.
Core Challenge Addressed: In high-salinity wastewater evaporation, chloride-induced pitting corrosion, crevice corrosion, and severe scaling/fouling (due to boiling point elevation of concentrated brine) are the primary failure modes of conventional austenitic stainless steel heat exchange tubes. This product is purpose-built to overcome these limitations.
2. Material & Properties
2.1 Available Tube Materials
- 2507 Super Duplex Stainless Steel (UNS S32750): A high-alloy duplex austenite-ferrite microstructure with a Pitting Resistance Equivalent Number (PREN) of ≥ 40, offering superior resistance to chloride-induced localized corrosion. Yield strength approximately 550 MPa, tensile strength ≥ 620 MPa.
- Titanium Grade 1 (ASTM B348 / EN 12457): Near-pure titanium (≥ 99.0% Ti), offering exceptional corrosion resistance in chloride-rich environments with negligible galvanic potential concerns. Preferred for the highest chloride concentrations and acidic conditions.
- Titanium Grade 2 (ASTM B348 / EN 12457): Commercially pure titanium with slightly higher mechanical strength than Grade 1, suitable for applications requiring enhanced pressure containment.
2.2 Key Performance Characteristics
| Property | 2507 Super Duplex (UNS S32750) | Titanium Grade 1 |
|---|---|---|
| Pitting Resistance (PREN) | ≥ 40 | N/A (inherently resistant) |
| Maximum Service Temperature | 300 °C | 350 °C |
| Yield Strength (0.2% Offset) | ≥ 550 MPa | ≥ 275 MPa |
| Tensile Strength | ≥ 620 MPa | ≥ 450 MPa |
| Corrosion Resistance in Cl⁻ > 50,000 ppm | Excellent (with proper flow velocity) | Outstanding |
| Boiling Point Elevation Tolerance | Up to +15 °C | Up to +20 °C |
| Scaling/Fouling Mitigation | Forced circulation + online cleaning interface | Forced circulation + online cleaning interface |
| Standard | ASTM A790 / EN 10217-7 | ASTM B348 / EN 12457 |
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | 19 mm, 25 mm, 32 mm, 38 mm, 51 mm (custom sizes available) |
| Tube Wall Thickness | 1.5 mm – 3.0 mm (selected based on pressure rating and corrosion allowance) |
| Tube Length | Up to 12,000 mm (coiled configuration; straight sections available) |
| Coil Diameter | Custom range: 500 mm – 3,000 mm (based on shell-side geometry) |
| Operating Pressure (Tube Side) | Up to 4.0 MPa (design dependent) |
| Operating Pressure (Shell Side) | Up to 2.5 MPa (design dependent) |
| Design Temperature | -20 °C to +180 °C (process side) |
| Circulation Mode | Forced Circulation — external pump-driven flow to prevent tube blockage and ensure uniform heat transfer |
| Flow Velocity (Tube Side) | 2.0 – 4.0 m/s (optimized for fouling control and erosion prevention) |
| Online Cleaning Interface | Integrated CIP (Clean-In-Place) ports with quick-disconnect couplings for periodic chemical/physical cleaning without system shutdown |
| End Connection | Flanged (ASME B16.5 / EN 1092-1), threaded, or welded (butt-welded with 100% RT inspection) |
| Surface Finish (Tube ID) | Electropolished or mechanically polished to Ra ≤ 0.8 μm (reduces scaling nucleation sites) |
| Surface Finish (Tube OD) | Mirror polished or satin finish (enhances convective heat transfer coefficient) |
| Heat Transfer Coefficient (U-value) | 800 – 1,500 W/(m²·K) (depending on fluid properties and flow conditions) |
4. Manufacturing Process
- Raw Material Selection & Verification: Certified 2507 Super Duplex or Titanium Grade 1/2 seamless tubes sourced from approved mills (e.g., Outokumpu, Sandvik, VSMPO). Full mill test certificates (MTC) conforming to EN 10204 Type 3.1 are verified prior to fabrication.
- Dimensional Inspection: Incoming tubes undergo ultrasonic thickness measurement, OD/wall tolerance verification, and visual inspection per ASTM E797.
- Coiling & Forming: Precision CNC-driven coiling machines form tubes into the specified coil geometry with controlled bend radius (minimum 5D) to prevent wall thinning and micro-cracking. Cold-forming processes are used for 2507 duplex; warm-forming (with interpass annealing) is applied for titanium tubes to avoid work hardening.
- Welding & Joining: All weld joints are performed using Tungsten Inert Gas (TIG/GTAW) welding with argon back-purging (oxygen content < 20 ppm) to maintain metallurgical integrity. For 2507 duplex, welding parameters are controlled to avoid sigma-phase precipitation (temperature window: 200–400 °C interpass). For titanium, welding is conducted in a clean room environment with high-purity argon shielding.
- Non-Destructive Testing (NDT): 100% Radiographic Testing (RT) per ASME V Article 2 and Penetrant Testing (PT) per ASTM E165 on all welds and critical bends. Eddy Current Testing (ECT) per ASTM E709 for tube wall integrity verification.
- Surface Finishing: Interior surfaces are electropolished (for 2507) or acid-passivated (for titanium) to achieve the specified Ra values, minimizing scaling nucleation sites and reducing maintenance intervals.
- Hydrostatic Pressure Testing: Each coil assembly is pressure-tested at 1.5× design pressure for a minimum hold time of 30 minutes, with zero leakage tolerance.
- Online Cleaning Interface Installation: CIP ports are fabricated and welded at designated intervals along the coil, with quick-disconnect couplings installed for field serviceability.
- Final Inspection & Documentation: Complete quality dossier including MTCs, NDT reports, pressure test certificates, dimensional drawings, and material traceability records.
5. Applications
5.1 Primary Application: High-Salinity Industrial Wastewater Evaporation
This coiltube is specifically designed for evaporator systems treating wastewater streams with chloride concentrations exceeding 50,000 ppm, commonly encountered in:
- Chemical & Petrochemical Industry: Evaporation of spent chloride-containing process water, acid regeneration streams, and chlor-alkali wastewater.
- Pharmaceutical Manufacturing: Treatment of high-salinity effluent from API synthesis and fermentation processes.
- Electroplating & Metal Finishing: Concentration of cyanide- and chloride-containing plating baths for resource recovery and disposal reduction.
- Seafood Processing & Aquaculture: Evaporation of brine-rich process water and cleaning effluent.
- Textile Dyeing & Printing: Treatment of high-salt dye bath wastewater containing chloride-based mordants.
- Coal Chemicals & Methanol Production: Evaporation of high-chloride wastewater from water-gas shift and purification units.
5.2 System Integration
- Multi-Effect Evaporators (MEE): Typically 3-effect to 6-effect configurations for energy-efficient concentration.
- Mechanical Vapor Recompression (MVR) Evaporators: Low-temperature evaporation with high thermal efficiency.
- Forced Circulation Evaporators (FCE): External circulation pump ensures high-velocity flow through the coiltube bundle, preventing deposition of scale-forming salts (NaCl, Na₂SO₄, CaSO₄) on tube surfaces.
6. Unique Selling Points
- Proven Chloride Corrosion Resistance: 2507 Super Duplex (PREN ≥ 40) and Titanium Grade 1 materials provide guaranteed performance in Cl⁻ > 50,000 ppm environments where conventional 316L or 316Ti fail within months.
- Forced Circulation Anti-Blockage Design: Engineered for external pump-driven circulation at 2.0–4.0 m/s, effectively preventing tube blockage caused by crystalline scale deposits and maintaining consistent heat transfer performance.
- Integrated Online Cleaning Interface: Built-in CIP ports enable periodic cleaning without system shutdown, reducing unplanned downtime and extending service intervals between major maintenance events.
- Boiling Point Elevation (BPE) Tolerance: Materials and design accommodate BPE up to +15–20 °C, ensuring dimensional stability and corrosion resistance even as brine concentration increases during the evaporation process.
- Customizable Coil Geometry: Tailored coil diameters and configurations to fit existing evaporator shell dimensions, enabling retrofit applications as well as new installations.
7. Quality Certifications & Standards Compliance
| Standard / Certification | Scope of Compliance |
|---|---|
| ISO 9001:2015 | Quality Management System for manufacturing and fabrication |
| ASTM A790 / A790M | Welded Seamless 2507 Super Duplex Stainless Steel Tubing |
| ASTM B348 / B348M | Seamless Titanium and Titanium Alloy Tubing |
| EN 10217-7 | Non-alloy and Alloy Steel Tubes — Technical Delivery Conditions for Super Duplex |
| EN 12457 | Titanium and Titanium Alloys — Products, Chemical Composition, Mechanical Properties |
| ASME BPV Code Section VIII Div. 1 | Pressure Vessel and Heat Exchanger Construction (where applicable) |
| ASME V Article 2 | Non-Destructive Examination — Radiographic Testing |
| ASTM E165 | Penetrant Testing Methods for Welds and Castings |
| ASTM E709 | Eddy Current Examination of Non-Ferrous Tubes |
| EN 10204 Type 3.1 | Test Report with Additional Material-Specific Information |
| NACE MR0175 / ISO 15156 | Sulfide Stress Cracking Resistance (for 2507 in sour service scenarios) |
8. Ordering Information
To specify this product, please provide the following parameters to Wenzhou Jixing Metal Materials Co., Ltd:
- Wastewater composition analysis (total dissolved solids, Cl⁻ concentration, pH, temperature, presence of oxidizing agents)
- Evaporator type (MEE, MVR, FCE) and number of effects
- Required tube material (2507 Super Duplex or Titanium Grade 1/2)
- Tube OD, wall thickness, and total effective heat transfer length
- Operating pressure and temperature on both tube side and shell side
- Required coil diameter and configuration
- Connection type (flanged, welded, threaded)
- Number and location of online cleaning interfaces
- Applicable design code and jurisdictional requirements
Wenzhou Jixing Metal Materials Co., Ltd — Engineering Excellence in High-Performance Stainless Steel and Titanium Heat Exchange Solutions for the Most Demanding Industrial Environments.